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Comet '''81P/Wild''', also known as '''Wild 2''', is a [[comet]] named after [[Switzerland|Swiss]] astronomer [[Paul Wild (Swiss astronomer)|Paul Wild]] (pronounced ''Vilt''), who discovered it in 1978.
Comet '''81P/Wild''', also known as '''Wild 2''', is a [[comet]] named after [[Switzerland|Swiss]] astronomer [[Paul Wild (Swiss astronomer)|Paul Wild]] (pronounced ''Vilt''), who discovered it in 1978.It Had 18 nebula s and 962 bonbons


It is believed that for most of its 4.5 billion-year lifetime, Wild 2 had a more distant and circular [[orbit]]. In September 1974, it passed within less than one million kilometers of the planet [[Jupiter (planet)|Jupiter]], whose strong gravitational pull [[Perturbation (astronomy)|perturbed]] the comet's orbit and brought it into the inner [[solar system]].<ref name=kronk> {{cite web |first=Gary W. |last=Kronk|year=2001–2005 |title=81P/Wild 2 |url=http://cometography.com/pcomets/081p.html |accessdate=2008-10-23 }} ([http://cometography.com Cometography Home Page])</ref> Its [[orbital period]] changed from 43 years to about 6 years,<ref name=kronk/> and its [[perihelion]] is now about 1.59 AU ([[astronomical unit]]).<ref>{{citeweb|title=81P/Wild - Orbital Elements|url=http://cfa-www.harvard.edu/iau/Ephemerides/Comets/0081P.html|publisher=harvard.edu|accessdate=2008-03-05}}</ref>
It is believed that for most of its 4.5 billion-year lifetime, Wild 2 had a more distant and circular [[orbit]]. In September 1974, it passed within less than one million kilometers of the planet [[Jupiter (planet)|Jupiter]], whose strong gravitational pull [[Perturbation (astronomy)|perturbed]] the comet's orbit and brought it into the inner [[solar system]].<ref name=kronk> {{cite web |first=Gary W. |last=Kronk|year=2001–2005 |title=81P/Wild 2 |url=http://cometography.com/pcomets/081p.html |accessdate=2008-10-23 }} ([http://cometography.com Cometography Home Page])</ref> Its [[orbital period]] changed from 43 years to about 6 years,<ref name=kronk/> and its [[perihelion]] is now about 1.59 AU ([[astronomical unit]]).<ref>{{citeweb|title=81P/Wild - Orbital Elements|url=http://cfa-www.harvard.edu/iau/Ephemerides/Comets/0081P.html|publisher=harvard.edu|accessdate=2008-03-05}}</ref>

Revision as of 14:26, 16 January 2009

81P/Wild
File:Comet wild 2 craters.JPG
Enhanced image from the Stardust spacecraft
Discovery
Discovered byPaul Wild
Discovery date1978
Designations
1978 XI; 1984 XIV;
1990 XXVIII
Orbital characteristics
EpochMarch 6, 2006
Aphelion5.308 AU
Perihelion1.592 AU
Semi-major axis3.45 AU
Eccentricity0.5384
Orbital period6.408 a
Inclination3.2394°
Last perihelionSeptember 25, 2003
Next perihelion2010

Comet 81P/Wild, also known as Wild 2, is a comet named after Swiss astronomer Paul Wild (pronounced Vilt), who discovered it in 1978.It Had 18 nebula s and 962 bonbons

It is believed that for most of its 4.5 billion-year lifetime, Wild 2 had a more distant and circular orbit. In September 1974, it passed within less than one million kilometers of the planet Jupiter, whose strong gravitational pull perturbed the comet's orbit and brought it into the inner solar system.[1] Its orbital period changed from 43 years to about 6 years,[1] and its perihelion is now about 1.59 AU (astronomical unit).[2]

Nucleus parameters

Stardust Mission

NASA's Stardust Mission launched a spacecraft, named Stardust, on February 7, 1999. It flew by Wild 2 on January 2, 2004 and collected particle samples from the comet's coma, which were returned to Earth along with interstellar dust it collected during the journey. 72 close-up shots were taken of Wild 2 by Stardust. They revealed a surface riddled with flat-bottomed depressions, with sheer walls and other features that range from very small to up to 2 kilometres across. These features are believed to be caused by impact craters or gas vents. During Stardust's flyby, at least 10 gas vents were active. The comet itself has a diameter of 5 kilometres.

Stardust's "sample return canister," was reported to be in excellent condition when it landed in Utah, on January 15, 2006. A NASA team analyzed the particle capture cells and removed individual grains of comet and interstellar dust, then sent them to about 150 scientists around the globe.[6] NASA is collaborating with The Planetary Society who will run a project called "Stardust@Home," using volunteers to help locate particles on the Stardust Interstellar Dust Collector (SIDC).

So far,[7] the composition of the dust has contained a wide range of organic compounds, including two that contain biologically usable nitrogen. Indigenous aliphatic hydrocarbons were found with longer chain lengths than those observed in the diffuse interstellar medium. No hydrous silicates or carbonate minerals were detected, which suggests a lack of aqueous processing of Wild 2 dust. Very few pure carbon (CHON) particles were found in the samples returned. A substantial amount of crystalline silicates such as olivine, anorthite and diopside were found,[8] materials only formed at high temperature. This is consistent with previous observations of crystalline silicates both in cometary tails and in circumstellar disks at large distances from the star. Possible explanations for this high temperature material at large distances from Sun were summarised before the Stardust sample return mission by van Boekel et al:[9]

Both in the Solar System and in circumstellar disks crystalline silicates are found at large distances from the star. The origin of these silicates is a matter of debate. Although in the hot inner-disk regions crystalline silicates can be produced by means of gas-phase condensation or thermal annealing, the typical grain temperatures in the outer-disk (2−20 au) regions are far below the glass temperature of silicates of approx 1,000 K. The crystals in these regions may have been transported outward through the disk or in an outward-flowing wind. An alternative source of crystalline silicates in the outer disk regions is in situ annealing, for example by shocks or lightning. A third way to produce crystalline silicates is the collisional destruction of large parent bodies in which secondary processing has taken place. We can use the mineralogy of the dust to derive information about the nature of the primary and/or secondary processes the small-grain population has undergone.

Results from a study reported in the September 19, 2008 issue of the journal Science has revealed an oxygen isotope signature in the dust that suggests an unexpected mingling of rocky material between the center and edges of the solar system. Despite the comet’s birth in the icy reaches of outer space beyond Pluto, tiny crystals collected from its halo appear to have been forged in the hotter interior, much closer to the sun.[10]

Gallery

References

  1. ^ a b Kronk, Gary W. (2001–2005). "81P/Wild 2". Retrieved 2008-10-23. (Cometography Home Page)
  2. ^ "81P/Wild - Orbital Elements". harvard.edu. Retrieved 2008-03-05.
  3. ^ "Comet 81P/Wild 2". The Planetary Society. Retrieved 2008-12-16.
  4. ^ D. T. Britt; G. J. Consol-magno SJ; W. J. Merline (2006). "Small Body Density and Porosity: New Data, New Insights" (PDF). Lunar and Planetary Science XXXVII. Retrieved 2008-12-16.{{cite web}}: CS1 maint: multiple names: authors list (link)
  5. ^ Using the volume of an ellipsoid of 5.5x4.0x3.3km * a rubble pile density of 0.6 g/cm³ yields a mass (m=d*v) of 2.28E+13 kg
  6. ^ "Scientists Confirm Comet Samples, Briefing Set Thursday". nasa.gov. Retrieved 2008-03-05.
  7. ^ "Light element isotopic compositions of cometary matter returned by the STARDUST mission" (PDF). Lawrence Livermore National Laboratory. Retrieved 2008-03-05. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
  8. ^ "Comet from coldest spot in solar system has material from hottest places". uwnews.org. Retrieved 2008-03-05.
  9. ^ "The building blocks of planets within the `terrestrial' region of protoplanetary disks". ukads.nottingham.ac.uk. Retrieved 2008-03-05.
  10. ^ Comet Dust Reveals Unexpected Mixing of Solar System Newswise, Retrieved on September 18, 2008.

External links


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